Combination electrical and fluid conducting cable



Feb. 25, 1947. F. G. ALBIN COMBINATION ELECTRICAL AND FLUID CONDUCTINIG CABLE Filed June 29, 1943 fa-'052mg G. ALs/N,

ATTORN EY.

Patented Feb.A 2.5, 1947 COMBINATION ELECTRICAL AND FLUID l CONDUCTING CABLE Frederick G. Albin, Los Angeles, Calif., asslg'nor to Radio Corporation of America, a corporation of Delaware Application June 29, 1943, Serial No. 492,692

1 Claim.' (Cl. 17d-45)' This invention relates to heating devices and particularly to a cable for simultaneously conducting high or radio frequency current and a iluid, such as air, for cooling purposes.

In R. A, Bierwirth Patent No. 2,314,865 of March 30, 1943, and H. C. Gillespie Patent No. 2,314 875 of March 30. 1943, devices for heating articles by induction from a source of electrical energy of high frequency, are disclosed and claimed. These devices comprise a single-turn coupling coil coupled to a high frequency oscillator through a step-down transformer. the coupling coil providing a high, concentrated magnetic field which induces eddy currents in a conductive article which is to be heated. Since the windings of the transformer become quite hot, a stream of air is caused to pass over the windings to cool them. 'I'his :dow of air is the result of the Venturi action of a i'low of compressed air supplied by a compressor.

In the above-mentioned patents, an electrical cable is employed for conducting the high frequency energy from the oscillator to the primary winding of the transformer, and a separate hose is used for connecting the air compressor storage tank with the transformer. The present invention is directed to a combination electrical conductor and air hose which is particularly efilcient as an electrical conductor and an air hose, while being of small diameter, flexible, and light in weight. y

'Ihe principal object of the present invention, therefore, is to facilitate the transmission of electrical energy between a source and a load while simultaneously conducting a cooling iiuid such as air.

Another object of the invention is to provide an improved combined electrical and air conductor.

A further object of the invention is to provide an improved ilexible electrical conductor for high frequency currents which simultaneously is adaptable to conduct air therethrough for coolins purposes'. A

Although the novel features which are believed to be characteristic of this invention will be pointed out with particularity in the appended claims, the manner of its organization and the mode of its operation will be better understood by referring to the following description read in conjunction with the accompanying drawingsl forming a part hereof, in which:

Fig. 1 isa diagrammatic view partly in section,

illustrating the general heating device embodying the invention, and,

Fig. 2 is an velevation view, partly cut away, showingthe invention,

Referring now to Fig. 1, a spool-shaped supporting member I of insulating material has wound thereon a primary winding 3 of a transformer coupled to a suitable high frequency oscillator 5 by a concentric electric cable and air hose I0, to be described in detail hereinafter, Surrounding the primary winding 3 and spaced therefrom by annular flanges 9 'and II formed on the ends of supporting member 4I is a single-turn secondary winding I3, the windings 3 and I3 being concentrically related and the anges 9 and I I providing an annular air space I5 between the two windings. The primary winding 3 consists of a number` of turns of wire of suitable diameter wound in a single layer on the supporting spool I and the secondary winding I3 may be made of a copper sheet of suitable thickness and length, being formed into a tube which surrounds the primary winding 3, and having one end I8 thereof extending beyond the primary winding 3 and the flange 9.

Mounted on the extending portion I8 of the secondary winding I3 is a frusto-conical coupling coil I'I constituting an inductor tip and having a relatively small diameter at its apex end. When the system is set up for operation, the oscillator 5 supplies energy to the primary winding 3 where. by a high current is induced in the secondary winding I3 and the coupling coil I1 connected i thereto. In this manner, therevis set up at the apex end of the coil I'I a highly concentrated magnetic field which, if brought into proximity with the article to be heated. such as the head of a rivet, the rivet will become heated by the eddy currents induced therein by the concen-y trated magnetic eld.

To effect the proper cooling of the windings 3 and I3 and also the inductor tip I'I, there is formed on the projection of the secondary wind- .ing I3, a radially inwardly-directed tubular member 25. This member may bey formed either by spinning, or by brazing or otherwise suitably connecting it tothe secondary winding I3. The secondary winding I3 is also provided with one or more circumferentially distributed openings I4 and the iiange 9 is provided with a plurality of circumferentially distributed openings 8, the openings I4 permitting air to pass to the annular passage way I5 from which it passes through openings 8 into the portion I8 of the secondary winding I3. A nozzle 2l extends into the tubular member 25 and is of suiilciently small diameter to be 'spaced therefrom. The nozzle 21 facing indulctortipil.

' eclater For further detailed explt tion of this 'trans- :learner system, ifeierence is made to the abovenientioned Gillespie Patent No. 2,3l75 in I dielectric constant because of the high percentage of air voids. Although the Celanese braid meets these requirements very satisfactorily,

other satisfactory materials are glass, polystyrene, silk, wool, and the like.

Over the braid si is the second electrical .con-

doctor di of tinned copper braid having a terwhich is encarnan electrical energy conducting entre connectecjtetween the ry win a and the oscillatc t, and a seperate air'hose connested betweenthe nozzle' 2i and the storage tant. l2. ln thtpresent invention-the electrical conducting cable and hose are combined into a einlc unit which is flexible, of light Weight, and

a particularly ecient electrical conductor.

This combination fluid and electrical conductor cable is sharm in detail in Fig. 2 which will now be referred to. e cylindrical element which forms the core of the cable is a ilexible metal hose St formed of spiral steel wire, the hose having an inside diameter of approximately 1% of an inch and an outside diameter of apl proximately V4 of an inch. This core prevents any crushing of the cable and maintains a clear air passage at all times. Over this core is a'steel or bronze braid which is covered by a braided, tlnned, copper conductor @t having an extension 31 for making connections with the oscillator 5 at one end, andvwith the primary winding 3 at the other end. Although the copper conductor may be oi any'suitable construction, one form minai extension lit. f This conductor has negli- -gible loss compared-with the inner conductor 38 because of lits larger diameter. 'Ihe second conductor is covered .with 'a cotton wrap M over `which an outer jacket or sleeve Q5 of rubber is placed to make the entire cable of approximately one 'inch outside diameter, the outer rubber covering being sumciently tough to wear well duringuse.` To connect the inner core 25 to the hose 2 9 and to the storage tant: i2, a rubber sleeve or hose is slipped over the steel core as shown at by the stippling. This sleeve or hose may vary in thickness in accordance with the pressure of the airto be conducted.

This particular cable structure is notonly a highly eillcient conductor from the standpoint of transmission of high frequency current, but is also capable of transmitting a cooling iluid `under considerable pressure. In combination with these necessary qualities, the cable is of small diameter and particularly iexible, which permay be la braid of 256 strands of .005 inch copper wire. The tensile strength or the cable is primarily provided by these braids which are j prevented fromvcollapsing radially by the steel core. this internal construction providing the maximum of exibility with a small diameter.

' Over this tinned lcopper conductor, a cotton wrap wie placed followed by a thin sleeve 40 of rubber orothensuitable dielectric material. The cotton wrap prevents the copper conductor frolzn oxidizing from the sulphur in the rubber sleeve, while the 'rubber sleeve. lserves two purposes. First, it maires the cable air and liquid tight, and second, it prevents broken strands of the braided' inner conductor't from projecting into a Celanese braided insulation layer M covering the rubber sleeve, the Celanese being a cellulosic plastic compound. Any projecting strands into the braid 6l would lower the breakdown potential. Although rubber is 'very satisfactory for this purpose, any' homogeneous tough. gum substance may be substituted. The Celanese braid 4i provides the'principal insulation and the strength against internal pressure, and the rubber sleeve need not, therefore, be capable of withstanding this pressure. The dielectric properties of the insulation material should be such that the loss factor is'low at high frequencies, andthe dielectric strength is high. The loss fector'variee with the dielectric constant. "l'hus, the braid is low in loss factor ce it is low in Number mits the heating device,l shown at the left inv Fig. l, to be readilymovedand emciently manipulated about the work.

I claim as my invention: A flexible electric cable for simultaneously conducting high frequency electric currents and compressed air comprising a nexible wire hose,

a braided copper electric conductor about said hose, alayer of resilient air and water tight ma.- terial surrounding said conductor, a textile wrapping interposed between the conductor and the layer of resilient material, a 'primary insulation of braided material having a low loss factor at high frequencies surrounding the resilient material, a, second braided electrical conductor surrounding said insulating material and said resilient material, a textile wrapping on said second conductorand an outer insulating jacket'` about said wrapping.

ERICK G. IN

VREFERENCES CITED The following references are of record in the file of this patent:

sra'rns Name Date 2,193,977 2,222,574 2,157,377 2,047,152 2,241,687 2,342,736

Robertson Nov. 19, 1940 Zink May 9, 1939 Mitchell July 7, 1936 Warnke May 13, 1941- ,l-lierzog Feb. 29, 1944 FOREIGN PATENTS Number Martin Mar. i9, 1940 

